Polymer sheets that can be used as interlayers in light-transmitting, multiple layer laminates, such as laminated safety glass or polymeric laminates, typically comprise poly(vinyl butyral). Laminated safety glass generally refers to a transparent laminate comprising a poly(vinyl butyral) sheet disposed between two panes of glass. Laminated safety glass often is used to provide a transparent or decorative barrier in architectural and automotive openings. Its main function is to absorb energy, such as that caused by a blow from an object, without allowing penetration through the opening. The function of poly(vinyl butyral) in the laminated safety glass is to prevent glass from forming sharp fragments after the glass is broken, to offer the penetration resistance to the glass, and to provide other functions, such as aesthetic functions and decoration.
Although poly(vinyl butyral) is well suited in general for use as a polymer sheet in safety glass interlayers, alternative materials are often useful as well. For example, poly(ethylene-co-vinyl acetate) (EVA) and polyurethane have both been used as interlayers in glazing laminates.
Interlayer materials are chosen for, among other reasons, improved handling, reduced cost of production, and improved performance. For applications in which the interlayer is not optically transparent and contributes to the aesthetic appeal of the glazing, interlayer materials are chosen for their appearance. Such applications include, for example, architectural applications in which a protective, decorative barrier between two spaces is desired.
Accordingly, further improved materials for use as an interlayer or part of an interlayer in multiple layer glass panels are needed in the art.